U.S. Pat. No. 4,049,452, issued to Nekut on Sep. 20, 1977, discloses a method for producing a screen structure employing a photoresist consisting of at least one diol ether or diol alkane and a polymeric material the solubility of which in a solvent is altered when it is exposed to light. The resist is coated on a support surface to form a film which is then exposed to an image in the form of light to selectively alter the solubility of the irradiated regions thereof. The more soluble regions of the film are removed, baring areas of the support surface, and a light-absorbing coating is deposited on the bare areas of the support surface and on the retained, less soluble, film regions. Then, a suitable etchant is applied to remove the retained film regions and the light-absorbing coating thereon, while retaining the light-absorbing coating on the support surface, thus forming openings, or windows, and creating the light-absorbing matrix.
The glycols and alcohols disclosed in the above-referenced patent, as well as other commonly used polar additives with hydroxyl functionality that are added to the polymeric material to form the resist solution, are highly sensitive to thermal and dark reactions and thus to the temperature of the support surface and the film drying process. While high sensitivity of the resist solution to light is desirable, a high sensitivity to heat or susceptibility to chemical reaction is undesirable since it causes non-uniformity in the resist film and variations in removal of the retained film regions, resulting in a reduction in sharpness, or edge definition, of the windows formed in the light-absorbing matrix.
The problem to which the present invention is directed is that of providing a photosensitive resist composition for the production of luminescent screen structures with a light-absorbing matrix for a color television picture tube, which composition maintains high sensitivity to light but substantially reduced "dark" hardening and thermal sensitivity.